Representative of the closest known prior art are: U.S. Pat. No. 3,893,453 to H. E. Goldberg, et al, filed Feb. 11, 1974, issued July 8, 1975, entitled "Compressed Data Display System"; U.S. Pat. No. 3,789,426 to J. M. Farlow, filed Dec. 29, 1972, issued Jan. 29, 1974, entitled "Facsimile Drive Apparatus"; U.S. Pat. No. 4,179,118 to C. P. Huss, filed Sept. 8, 1977, issued Dec. 18, 1979, entitled "Apparatus And Method For Releasably Securing Sheet Material To The Drum Of A Drum-Type Facsimile Machine"; U.S. Pat. No. 3,906,512 to J. M. Farlow, original filed Dec. 29, 1972, issued Sept. 16, 1975, entitled "Mechanical Drum Positioning And Sheet-Clamping Mechanism For Facsimile"; U.S. Pat. No. 2,906,586 to D. W. Collier, filed Jan. 7, 1955, issued Sept. 29, 1959, entitled "Sheet Record Machine"; U.S. Pat. No. 2,783,048 to B. Roberts, original filed Apr. 10, 1947, issued Feb. 26, 1957, entitled "Magnetic Recording System". Other patents considered relative to the present invention are: U.S. Pat. Nos. 4,241,405 to M. A. Allocca, filed Aug. 7, 1978,issued Dec. 23, 1980,, entitled "Database Updating Apparatus"; U.S. Pat. No. 4,123,182 to N. Kondur, Jr., filed May 17, 1976, issued Oct. 31, 1978, entitled "Cam Drive For Matrix Print Heads And The Like"; and U.S. Pat. No. 3,955,663 to M. E. Ecker, filed Dec. 23, 1974, issued May 11, 1976, entitled "Incremental Advance Mechanism".
The advent of low cost home computers, small office computers and word processing equipment has led to a great deal of interest in decreasing the size and cost and increasing the functions of printers used as output devices for these data processing and office products. There has also been a requirement for scanning devices such as those used in facsimile systems to encode for storage or communicate previously noncoded information derived from existing documents.
For both the printer and scanner environments some type of automatic paper handling capability greatly increases the function of this equipment. Further, any increase in speed that is possible as a result of a particular design inherently increases the function of the input or output device.
With regard to the technology of supporting a document for the printing or scanning operation, itself, the drum-type paper retaining approach shown in U.S. Pat. No. 3,893,453 is an attractive approach in view of the economy offered by providing drum rotation and a lead screw driven lateral translation carrier from a single motor. No means are shown in this patent, however, relative to any automatic loading or unloading of the paper. U.S. Pat. No. 3,789,426 is another example of a drum-type scanning apparatus. U.S. Pat. Nos. 4,179,118 and 3,906,512 show two types of remotely actuated paper clamps that may be used in conjunction with drum-type document retaining devices. U.S. Pat. No. 2,783,048 shows a dictating machine in which a flexible magnetic recording rectangular sheet is secured to the drum by an adhesive strip on the sheet. U.S. Pat. No. 2,906,586 also shows a dictating machine using a magnetic recording sheet. In neither of these machines using magnetic recording sheets is there shown a mechanism for feeding each of a stack of recording sheets, documents, or other information handling media onto and off of a drum-type document handling apparatus in a one-at-a-time succession. (In addition to the patents discussed above, U.S. Pat. Nos. 3,955,663, 4,241,405, 4,123,182 were considered relative to this invention but were not felt to be at all pertinent to the invention as claimed.)
Another aspect of paper handling that adds significant function to any paper handling system is the ability to handle the document within the system so that operations such as printing or scanning can be performed on both sides of the document. This feature is known in the paper handling art as duplexing, and in a printing system duplexing allows a sheet of paper to be printed upon on both sides.
It would, therefore, be highly advantageous to provide a duplexing function as an enhancement to an efficient paper handling system without adding significantly to the cost or complexity of the system.